The powerful bomb explosion outside the US consulate in Karachi comes at an awkward time for Pakistani President Pervez Musharraf.

Pressure is mounting on Musharraf to take action

The latest incident, which claimed at least eight lives, came only a day after the visit to Pakistan by US Secretary of Defence Donald Rumsfeld.

Mr Rumsfeld was in the region not only to persuade both India and Pakistan to defuse tensions, but also to discuss General Musharraf's military operations against al-Qaeda and other religious militants.

The US envoy expressed his satisfaction at the level of cooperation provided by the Pakistani authorities in hunting down al-Qaeda militants in the country.

But the Karachi bomb will pile further pressure on President Musharraf to bring Islamic militancy under control.

Paying the price

President Musharraf has expressed his determination to deal with militants on several occasions.

The blast could not have come at a worse time

But he is also aware of the intense pressure from the country's conservative Islamic lobby, which accuses him of succumbing to Western pressures at the cost of the country's religious ideology.

Observers say he faces a delicate balancing act between taking action against Islamic militants and ensuring that he is not seen as someone who has no regard for local sensitivities.

Whatever he does, the involvement of al-Qaeda and its Pakistani supporters is becoming a major problem for President Musharraf's administration.

Many believe the country is now paying the price for supporting the US-backed war against terrorism in Afghanistan.

This is now the fourth time this year that foreign nationals have specifically been targeted in Pakistan.

No leads

Militant groups seldom claim responsibility for attacks.

A little known outfit calling itself the National Movement for the Restoration of Pakistani Sovereignty, said it kidnapped US journalist Daniel Pearl in Karachi in January.

But that was an exception.

It is still unclear who was behind a grenade attack in March on a church in Islamabad attended mostly by foreign diplomats.